How do a make a really cool exploding volcano that involves fire?

Question

I made the baking soda vinegar one, and it was stupid, I want something more hard core, any ideas?

Answer 1

The best one I have seen is made using (NH4)2Cr2O7. However, I doubt you will find this in a normal store, as opposed to baking soda or vinegar. I love this experiment, so enjoy seeing it in action too :-)

N.B. It makes a huge amount of mess: the substance raises its volume several times and debris is spitted up in the air by the fire. Really effective and "hardcore". However, it's safe.