>Idk how these transformers suddenly blow but it was so loud and bright it felt like a movie for a sec

So transformers are two large coils of wire tightly wrapped around a loop of iron. One coil on one side of the loop is the input high voltage and on the other side of the loop is the low voltage output coil. That's the "transforming" going on - high voltage to low. The reason they can handle such high voltages in such a small space is because they're filled with an insulating oil separating the input from the output. Over time the oil leaks out in various ways. Once there's not enough insulator in between the input and output you get a short circuit, and the high voltage arcs over creating an arc flash. The temperature of an arc flash event is hotter than the surface of the sun iirc, so things like solids can temporarily turn into liquids, gasses, or maybe even plasma.

Tldr: they suddenly blow because the insulating oil leaked out and the high voltage gets to short circuit over to the low voltage side.