A recent case in Oklahoma has revived the old stories of spontaneous human combustion, where a person is quickly immolated from no apparent cause.
“Danny Vanzandt May Have Died from Spontaneous Human Combustion”
The notion of such an event has been believed by some and simultaneously disbelieved by others for centuries. Personally, I think people just like a good story, and if it's entertaining enough to tickle the imagination some will believe it. This article from a 1966 issue of Adam takes an entertaining yet skeptical view of the “phenomenon.”