The Perfect Volcano

Teacher bought a little plastic volcano holder. It says on the instructions that you can get the volcano to explode by filling it with bread soda, then adding vinegar. We tried this, and did get the volcano to erupt nicely. Not satisfied that this was the perfect volcano, we tried other combinations of powders and liquids.
We tried adding vinegar to baking powder - it leaked a little from the bottom of the volcano but didn't erupt properly.We also tried adding water to baking powder - this fizzed a little, but not enough to push the foam it made out the top of the volcano. I wonder what would happen if we tried adding a fizzy drink to icecream? We must try this some day.