Last year I found a dead deer in the woods. I put the head in a 5 gallon bucket and filled the bucket with grass clippings; I didn't skin it or do anything else to it. I left that in a hidden spot in my yard for about 8 weeks. It didn't smell and nothing messed with it. Pulled it out 8 weeks later and it was a bare skull with some bugs crawling around in the grass clippings.

That method is not for everyone I know, but for me it beats scrapping at a skull and trying to boil something outside.