Fast-casual restaurants have become increasingly popular over the past few years, with Chipotle (NYSE:CMG) leading the charge. But Chipotle isn't the only fast-casual chain growing fast, and the company will be facing plenty of competition in the coming years as smaller chains aim for rapid expansion. 

Click through the following slideshow to learn about five of the fastest-growing fast-casual chains: Chipotle, Shake Shack (NYSE:SHAK)Zoe's Kitchen (NYSE:ZOES)Noodles & Company (NASDAQ:NDLS), and The Habit Restaurants (NASDAQ:HABT).