To make the caramel, place the sugar, corn syrup, and 1/4 cup water in a large saucepan (large enough to hold the popcorn) and cook until the caramel turns a light golden brown. Add baking soda and butter to the caramel. Then add the popcorn to the hot caramel and stir with a wooden spoon until the popcorn is evenly coated.
Pour the caramelized popcorn onto a parchment-paper-lined baking sheet and set aside to cool. Break up the popcorn with your hands. Serve in colored-cellophane bags.