When I was in the 7th grade, we (Teacher and Kids) blew up balloons with acetylene and oxygen, used toilet paper for fuses and Exploded them in the School, outside the Metal Shop building, to demonstrate what happens if you accidentally leave the welding torch gas turned on. We also made explosives in science class to make sure us kids didn’t accidentally blow up the building. How far we have gone over the edge.
When we finally got to high school, and had real supplies to experiment with, many kids were known to make contact explosives out of iodine and other materials - don't remember the mix, never did it myself. Enough to startle folks, but not do much damage, if any at all.