The Explosion Will Be at Five (1984)

Original title: Výbuch bude v pět

This tale is about young Ludvik (Robert Nespor) an erstwhile, budding scientist whose practical sense leads him to experiment before his common sense has figured out the results. Due to that unfortunate pattern, he variously floods the bathroom while working on displacement of volume and weight in water, he shatters the harvest pumpkins but not the law of gravity, and now he is eyeing the neighbor's rabbits for an electricity experiment. While the rabbits remain safe for awhile, Ludvik's parents wish he would follow in their more traditional footsteps and dedicate himself to music. Instead, Ludvik has learned that the proper mixture of a certain carbide and water can be explosive, and while he works on that technique, a friend tips off the physics teacher about these potentially disastrous plans.