The Invisible Maniac (1990)

A budding young scientist lad is caught by his mom checking out the lady across the way with his telescope, whereupon she lectures him on the evils of women. Twenty years later and all grown up, the scientist announces his theories of invisibility, and his colleagues laugh, to which he responds by killing four of them. He escapes from the loony bin and gets a job teaching summer school physics at a high school. The students decide to tease him about the same time as he perfects his invisible juice, and he goes on a spree of vengeance.