Why did the meteor explode?
Rocky meteors tend to explode in the air due to uneven heating; the leading surfaces are hotter and thermal expansion causes the rock to burst.
Same as most things, rapid heating and expansion of vapor from material heated far beond its vaporization temperature. Aerodynamic heating tends to be asymmetric with non-linear heat transfer, so it’s likely there was a massive outgassing that just blew the non-melted pieces apart from the central mass.
Same as most things, blah, blah, blah..teehee...
Friction.