I don’t know about the entire film, but the nurse station scene in the Exorcist III is probably the scariest scene I’ve ever seen in my life. It probably didn’t help matters that I first saw it when I was like 12 years old and it scared me half to death.
I actually saw something not that long ago that had that scene as one of the best "jump scares" of all time. Like you I don't remember much else but that sure stuck.