The Avada Kedavra heard 'round the Wizarding World

[hokus7]

No: HPFGUIDX 135232

Hey all,

It's been discussed a bit recently, but nothing solid has been 
stated, so I'm posing this simple question:

Why the heck did Voldemort's Avada Kedavra that rebounded off Harry 
destroy his body?  We have no evidence of an AK ever destroying a 
body before -in fact, unless I'm mistaken, every other AK we've seen 
has left the body fully intact.  All I have are speculations: 

- Was it really an AK he fired?
- Was it a superpowered AK meant to ensure Harry was vaporized?
- Was/Is there something particular to Voldemort's biological makeup 
that made his body go "boom"?
- Was his body actually destroyed?  Was it the resultant explosion 
instead?  What caused the explosion, if so?

Basically, I'd just love to hear some theories on the question that 
I'm wondering about most right now.  I love theories :).

Hokus