Glad to hear that I'm not the only one this has happened to. I was getting paranoid with thinking about all the possible things I might have done wrong.
Could not think of any that was the problem!

Charged the pack after equalising to 0.9V/cell on Series 1 Novak smart tray on Ice set at 6Amp, 3mv/cell, normal charge.
Noted on smart tray one light went off very quickly, wrote that off as a below par cell in a matched pack.

After charge (4600 mAh, peak 9.17V no temp sensor but only moderately warm set this pack aside, ready to charge next pack.

After 20 minutes fitted pack to car to use Hudy setup board, setup car and left it in car.

Went to do other things, about 20 mins later heard a loud POP in the workshop, went in could not see anything (body on car) but could smell it.

Finally found cell endcap, black crap all over the chassis and inside of body.
What the........?

I have never had this happen before, sure..... shorted packs, over repeaked batteries, reversed esc connections, but this situation ......NEVER!!!

BTW the cell that let go was the same one that had early lights out on the Novak. Maybe someone can explain what that means...... No other explanation, not shorting out on chassis , not even hooked up to ESC

I'm carefully watching any IB pack now and even more so after reading this thread.... BTW day temp in the workshop was 27 deg celsius...

Lipos may be JUST as safe!