What happens to skin when you lose weight?

I'm very overweight and I've been trying to lose weight (need to drop more than 100 pounds). I'm not doing any fad diets or anything, but I revamped my diet, added exercise and strength training, and have upped how much water I drink. I'm only 23 and I don't smoke. What is going to happen to my skin once I lose this weight? I've already lost a little, and I've noticed a change in my skin, particularly on my stomach, where it's rippling, kinda like stretch marks but not a purple or red color. Will it bounce back? Or am I going to have saggy skin forever?