Movie theaters use butter-flavored oil, which has a lower water content than butter so it makes popcorn less soggy. Real clarified butter has the same effect. To make it, melt 2 sticks butter in a glass measuring cup in the microwave. Let sit for a few minutes; the butter will separate into 3 layers. Skim off the top layer of foam, then slowly pour the clarified butter into a heatproof container; discard the bottom layer of milk solids. Use 3 tablespoons hot clarified butter for 10 cups popcorn; refrigerate the rest (it's great for sauteeing).