I remember visiting a science museum as a kid which had a couple of CRTs like that set up where you could pull a rope to smash a hammer into it and try to break it. With the same result; never leaving a mark.

CRTs are built like that because otherwise they would implode from the slightest bump and send thousands of tiny glass fragments flying in all directions.

Panel displays of today have their glass pieces glued together into one solid lump, and there is no pressure, so when they break the broken pieces stay where they are for the most part.