I was watching a program on TV about spontaneous human combustion. The only thing is that spontaneous human combustion is so rare that it happens in the chances of like one in a million. The thorough investigation of the case proved that it was in fact not human combustion but instead microscopic spider-like machines that were in the particular person's blood. (they were placed there or some shit) Anyway, they were a-sexual. They could build themselves in a matter of seconds. This generating heat, and spreading the atoms out. (if you know that theory) Or they thought that the machines were controlled by remote.
Well, blla blaa bla, and shit I don't have time to tell but lets get this down.
The human exploded not even leaving ashes, only like one body part was left.

Our technology is advancing everyday, I do believe this is possible. I will go in deepth when I have time..till then feel free to respond or add information to this.