Growth stocks that can mimic the jaw-dropping returns on capital of the e-commerce upstart Shopify (NYSE:SHOP) are certainly few and far between. This fairly new face to red-hot online commerce space, after all, has seen its stock rise by a stellar 349% since going public in 2015.

So, with this rather challenging task in mind, we asked three Motley Fool investors which stocks they think might be able to outperform even Shopify in the years to come. They suggested Celldex Therapeutics (NASDAQ:CLDX), A.O. Smith (NYSE:AOS), and e.l.f. Beauty (NYSE:ELF)

Businessman pointing to upward trending chart.

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An unloved cancer stock 

George Budwell (Celldex Therapeutics): Small-cap cancer companies can be exceptional growth vehicles for long-term-oriented investors. While risky, this particular group of biotechs has produced a number of highfliers that have been some of the best-performing stocks of late -- such as bluebird bio, Juno Therapeutics, and TG Therapeutics. And I think the beaten-down cancer specialist Celldex Therapeutics could be the next company to join this list.

Celldex is a small-cap cancer company that's been on life support ever since the late-stage failure of its brain cancer vaccine known as Rintega. Although it did have other clinical assets under development at the time, this high-profile clinical setback seemingly sparked a loss of confidence among investors in the company's underlying ability to actually bring a product to market.

That dire sentiment, however, is about to get its first real test via the upcoming top-line readout for Celldex's experimental triple-negative breast cancer drug glembatumumab vedotin, or glemba.  

The long and short of it is that glemba is targeting an underserved patient population that should be able to support upwards of $500 million in peak annual sales. Now, glemba's clinical success is far from a sure thing, and that's a big reason why this company's market cap is only $375 million at this point. However, a positive readout in the drug's ongoing mid-stage trial will almost certainly trigger a radical revaluation in breakneck fashion. 

On the flip side, a second major clinical failure could lop off as much as, say, 50% of Celldex's present valuation, if not more. So this speculative biotech stock does have a dangerous side that shouldn't be ignored by investors on the hunt for unusual growth opportunities. 

More growth to come

Reuben Gregg Brewer (A.O. Smith): A.O. Smith does something incredibly boring: It makes water heaters. While you and I take the luxury of hot water for granted, residents moving up the socioeconomic ladder in developing nations don't. For these people, hot water is a luxury well worth the cost. But let's put a number on that: A.O. Smith's sales in China grew at an incredible compound annual rate of 22% over the 10 years through 2016. 

China makes up virtually all of the company's foreign sales (around a third of total sales). But I don't expect that to be the case for very long because A.O. Smith is moving aggressively into India. This Asian nation is just as large as China and holds significant growth potential as its residents move up the socioeconomic ladder, too. The water heater maker is planning on using the same sales tactics in India that succeeded so well in China.   

Although there's no reason to expect anything more than relatively stable sales in the company's more mature markets, notably North America, A.O. Smith's Asian opportunity is huge. And as that plays out, it should continue to drive results higher for years into the future. This may not be as exciting a name as a tech company like Shopify, but sometimes the things we take for granted are a bigger deal than we think.

Not putting lipstick on a pig

Rich Duprey (e.l.f. Beauty): You wouldn't know it by looking at e.l.f. Beauty's stock chart, but the mass-market cosmetics company is a growth stock you should seriously consider. Despite its shares losing more than 10% in one week and being down nearly 40% from their 52-week high, it promises an opportunity that could put Shopify's growth rate to shame.

E.l.f. cosmetics are appearing where people are shopping. These prestige products at affordable prices -- what e.l.f. calls "mass-tige" -- in Target, Wal-Mart, and beginning this year, in all Ulta Beauty (NASDAQ:ULTA) salons.

The concept of so-called fast-beauty, like fashion fashion -- a take on premier products at low prices -- is driving Ulta to expand its mass-market offerings to fend off inroads being made by Amazon.com (NASDAQ:AMZN). Cosmetics was the e-commerce leader's fast-growing category last year, growing 60% year over year, and Ulta sees products like e.l.f. Beauty differentiating it from rivals like Sephora.

The reason e.l.f.'s stock took a hit is that it recently cut its long-term adjusted EBITDA growth rate forecast from 20% to a range of 10% to 15%. While a seemingly dramatic drop, e.l.f. maintains it's more of a cyclical decline in the industry affecting everyone, and once the market bounces back, e.l.f. Beauty will, too.

With its stock depressed, it may represent the perfect opportunity to buy in ahead of the rebound. Particularly now that its products will be available in all 1,025 stores this year, that could come sooner than many expect.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. George Budwell has no position in any of the stocks mentioned. Reuben Gregg Brewer has no position in any of the stocks mentioned. Rich Duprey has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Amazon, Bluebird Bio, and Shopify. The Motley Fool recommends Celldex Therapeutics, e.l.f. Beauty, Inc., Juno Therapeutics, and Ulta Beauty. The Motley Fool has a disclosure policy.