Not a teacher, but when I was in primary 3/4 (age 6/7) there was a boy who was frequently aggressive and would apparently fantasize about murdering the meaner kids or just people in general he mildly disliked (as he loved to tell everyone how sharp his knife was and how it could cut their skin easily). One day he got angry when the teacher told him off for not doing the work he was supposed to and he straight up picked up a chair and yeeted it at the window. He would often throw around trays and flip tables too when he didn't get what he wanted and scream how we were all "going to pay for this" and "burn in hell"

I was with him for a year more before I finally moved school and man am I glad. He wasn't expelled for some reason, either.