Mentos Experiment Bust

Talked to 1 last night as he is at his grandmother's house in Texas. They were going to do the mentos in a 2 liter of soda trick. He was explaining to me that you drop a few mentos in the 2 liter and it will erupt like a volcano straight up in the air. Well he called back to tell me it was a bust! He was very disappointed but I told him that not to worry, Daddy will research this experiment and when he gets back here we will retry! I hope to have pictures of this!