You've seen it on hit YouTube videos, but now young researchers have unlocked the secret of the volcanic reaction that occurs when Mentos are dropped into Diet Coke, ABC News reports. Students at Appalachian State University say the rough, dimply surface of the sinking candy disrupts the water molecules in the soda to create powerful "bubble growth sites" that trigger geysers of foam that shoot upwards of 30 feet.
"If you drop a pack of Mentos into a bottle of Diet Coke, you get this huge fountain of spray and Diet Coke foam coming out," said the physicist who encouraged his students to study the effect. "This was a good project because there was still some mystery to it." (Read more Diet Coke stories.)