Back in the day, a neighbor used to make black powder from the three usual ingredients, all available from the local drug store.
The only time it went boom was when he was drying out a a bunch that had gotten damp.
He decided to hurry things up by heating the mix in a large pan on the stove.
It would still have probably been ok, had he not gotten side tracked doing something else, and left it simmering a little too long.
Even then, there was no real harm, other than a big flash and lots of smoke, that filled the basement and rolled out the windows.
He had some explaining to do when the fire truck showed up.
Lock the doors, they're coming in the windows.