What are the exhaust pops and cracks? I’ve heard two things. One, raw fuel is dumped out during the exhaust stroke and ignites in the catalytic converter. Two, the ignition fires very late in the power stroke and is still igniting the fuel mixture when the exhaust valve opens. Either (or neither) of these correct?

 

I think it's neither of those but your first guess is close.
That is, AFAIK small amounts of fuel are injected on the exhaust stroke and this fuel then ignites somewhere towards the rear of the exhaust system.
Not in the cats as that would destroy them and not in the rear muffler as that would destroy it but somewhere in the pipes before the muffler.
The raw/unburnt fuel passing through the cats eventually kills them.

 

How does the fuel pass through the catalytic converter without igniting? Isn’t the cat the hottest part of the exhaust system?

 

Knowing nothing about Jags other than what I read here, my understanding is that Jag reduced the popping because it was damaging the cats, and there are a number of pics on here showing "deconstructed" cats, which seems to back up the former.

 

I found this interesting clip on YouTube explaining the process leading to the crackles.

 

Just curious, but do our cars light up at night when we release the hammers of hell?

 

After watching the video, I wondered the same thing.