Any time you're caramelizing sugar you gotta add some sort of long chain polysaccharide (corn syrup, molasses, even pancake syrup)to get the whole thing going. Just a teaspoon. Keep stirring on medium heat---after it bubbles up a bit just keep dipping a tip of a spoon in it then in cold water. When it hardens in the cold water it's time-- add a little baking soda. The rapid change in Ph will make it foam up and coat the popcorn better. Oh and keep your popcorn hot in the oven. I have two large metal salad bowls to dump the popcorn in, add the foamed carmelized sugar to, then invert one bowl on the other and shake the heck out of it to coat everything evenly. Butter up your hands and start forming balls. You can add food color to the sugar mixture too if you want