High-flying growth stocks might be fun to buy and watch closely while they're hot. But when you're angling for strong 25-year returns to support your retirement savings, you'll need to invest in companies that are stable enough for you to sleep well at night. And that often means investing in large corporations that aren't exactly about to disrupt their industries.

Still, stability doesn't need to imply slow growth, nor does it need to mean being in a boring line of business. Let's put three of these stably growing giants under the microscope to find out why they're worth your consideration for purchase.

1. Vertex Pharmaceuticals

Vertex Pharmaceuticals (VRTX -0.92%) is an evergreen stock because it has proven that it's an expert at consistently extracting wild growth from a tiny niche. Of the 83,000 estimated patients living with the rare hereditary disease cystic fibrosis (CF) in the Western World, Vertex treats more than half of them with its portfolio of drugs, and it's doing a significant amount of research and development work to treat everyone that's left. As if its stellar market penetration isn't enough, from selling CF medicines alone, its trailing-12-month net income has grown by more than 1,150% in the last five years, reaching more than $2.4 billion.

What's more, Vertex is starting to diversify into developing therapies for other illnesses, ranging from type 1 diabetes to pain and Duchenne muscular dystrophy. That way, it'll gain access to new therapy markets if it eventually runs out of room to grow within the market for CF drugs. Over the next 25 years, it's likely that the company will have cornered multiple other niche markets, developing and recombining its commercialized medicines into new packages as it has done with CF to stay firmly ahead of the exclusivity protections expiring and denting revenue. And that'll make shareholders richer, just like the company's CF strategy did.

2. STAAR Surgical

Based on current trends, by the year 2050, nearly half of all people will be near-sighted (formally referenced as myopia). And in a world that's slated to produce more and more people with myopia over time, investing in a vision correction business like STAAR Surgical (STAA -3.51%) is a no-brainer. STAAR makes implantable lenses that replace other corrective technology like contact lenses or glasses, and that means it's competing in a market that is currently worth $70 billion per year. Unlike contacts or glasses, STAAR's implantable lenses don't have the hassle of getting torn, smudged, cracked, or otherwise mutilated, though they do require an outpatient surgical procedure to set up.

Most people with myopia probably won't want to get implantable lenses. But, so far, grabbing a small slice of the massive global market for vision correction has been quite lucrative for the company, with its trailing-12-month revenue rising by 281.4% in the last 10 years to surpass $242.9 million. And, over the last three years, its trailing-12-month net income jumped by an eye-popping 232.1%. Right now, STAAR is working its way into the Chinese market, where it already owns a share of more than 20% despite only starting to compete there in 2015. Better yet, it won't need to change much of anything about its business model or its product to keep growing at a moderate pace for the long run -- and that's why it's a favorable purchase today. 

3. Apple

Apple (AAPL 0.86%) is an obvious stock to buy and hold for decades because it's one of the strongest and most valuable brands in the world. It's also a favorite of legendary investors like Berkshire Hathaway CEO Warren Buffett, who holds so many shares that the company constitutes more than 42.7% of Berkshire's entire portfolio. And, through sales of its computers, software, and subscription services, Apple's quarterly free cash flow (FCF) rose by 115.9% over the last five years, meaning that it is constantly generating excess capital for reinvesting into new avenues for growth.

It also returns a huge amount of capital to its investors in the form of its dividend and share buybacks. While its forward dividend yield of around 0.6% isn't about to make anyone rich on its own, it's rising quite consistently over time, including most recently in the second quarter, when management opted to hike it by 5%. At the same time, the company authorized an additional $90 billion for its share repurchase program. Over the next 25 years, by continually hiking the dividend and buying back its shares, Apple will make today's investors much better off, and that's a compelling reason to buy the stock.