My wife and I tried an experiment. We took two, one gallon containers of Tree Top cider, added 1/8 cup of brown sugar to one, none in the other. We then added 1/5 of a slap pack of Wyeast Cider yeast to both gallons. A stopper and air lock were put on both bottles and we waited. Nothing happened for 36 hours. When I got home from work I had two blown stoppers, krauesen( does that apply the same with cider?) pouring out across the counter. I cleaned, re-sterilized, and replaced the stoppers and air locks, after pouring out a bit of cider. Tonight, two weeks later, we poured a glass. It foamed highly and smells very sour. Like the post says, what have I created? I am scared of it!