Actually calcium carbide is not the least bit explosive, but when you add water it generates acetylene gas which is explosive when mixed with air in just about any proportion. That's where the fun comes in.
But of course...having played with the stuff since about the age of 5, I guess I took it for granted that was a given, but I suppose I shouldn't have.
In my mid to late teens, while still living in the northeast, I became really involved in speleology, and found a brand new use for grad-dad's lamps. I still have them somewhere, and should probably dig them out and brasso them up.
As of the late 80's, the mounting brackets on helmets for the electric headlamps then in use were still compatible with the tabs on the carbide lamps. On one caving trip I had a spectacular, space shuttle-like O-Ring failure of the rubber gasket that sealed the carbide pot from the water reservoir. A rush of acetylene shot out of the pot, and hit the flame. I thought for a moment I was witnessing the second coming.
Ever do potato mortars?