Mine did that exactly the same thing this weekend, too...
tick tick tick tick..... tick tick tick tick..... tick tick BOOOM
My best guess is that it was a spider's nest, but I'm not positive. Ashes everywhere in the compartment. The difference is that mine is still working fine after the "kaboom". I have a list of things for the dealer to look at so I'll just add it.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD