What would it take for someone's head to explode?

Another thread mentions a mouse exploding from a huge electrical shock, which I would’ve given a “dubious” smiley if I had a good one to use. Naturally, I thought of Scanners (link to still image).

Bodies can explode from gas build-up when their owners have left the building, as police officers and coroners can tell you. Discrete internal organs in the living can from liquid buildup. (Gas buildup also?)

But short of that exquisitely effective power to make someone’s skull explode just by looking at them, what could do it?

Excluding anything “obviously” explosive such as a mini-bomb, blasting cap, etc. Although particularly creative or sneaky ways to introduce them would be interesting.

T E Lawrence, in “Seven Pillars of Wisdom”, described a man who was punished by being thrown into an oven alive. Lawrence said he could hear the popping sound of the head exploding from the dry heat, presumably after the unhappy offender had already died. How Lawrence knew it was the head was not explained.

Presumably, the skull is packed fairly tight with matter, and few air spaces, and the contents would expand under heat while the skull remained intact.

Does the skulls of frozen people crack, or do the brains just slowly squeeze out of the various holes in the skull?

High velocity rifle rounds seem to do the trick.

Too much knowledge, I reckon.

Exploding Head Syndrome.

(No, not really. It’s a real thing, but the actual symptoms are **very **disappointing when you hear about it for the first time)