Loud bang passenger side rear descending speed bump

Last night I had to drop my daughter-in-law off at an event, and the parking lot had really high speed bumps. So I crawled over them very slowly and all was fine until on the last one going in (5th?) I took my foot off the brake at the top (too soon), the car descended quickly, and there was a loud hard bang from the the passenger side, sounded like somewhere behind the passenger seat. There was no audible scraping sound with it though, or at any other time. Dropped her off, turned around and drove out over the same bumps, just as slowly and even more carefully, and nothing eventful happened going the other way.

I weigh 135 lb (driving), my son is 220 (front passenger), and the DIL 200? (not going to ask, I like living too much) was in the rear passenger, nothing else heavy in the car. So below max weight, but the majority of it on the passenger side. My floor jack is out of service at the moment but looking in from the side the muffler doesn't look scraped or damaged and no signs of a collision on the bottom of the body back there.

So maybe the passenger rear suspension hit the limiter on the rapid descent? Kind of surprising because I have gone over all sorts of bumps while driving and never had it bottom out before (if that is what it was.) The bump was high, but clearly not higher than the middle of the car, because nothing scraped while it was passing underneath. So it isn't like the car fell several feet, couldn't have been more than 5.4 inches. Tire inflation was 35/33 front/back, did that a couple of days ago. I'm thinking maybe the shock in that corner is going, but can't get under there at the moment to look at it for leaks. Will bounce the corners when my wife gets back from the store.

 

My son and I bounced the right rear corner hard (he was standing in the rear door opening, I was pushing on the hatch opening, the car was just shy of hopping off the ground) and we couldn't get it to do anything but squeak a little. That shock was working fine. Also got a better look at the muffler and it didn't have any dings or even a slight scrape on the bottom. Finally drove the right rear wheel off the edge of the driveway where it rises to curb height, so that corner would drop 6 inches suddenly, and still no bang.

So probably not hitting a stop. Can't rule out the possibility that the muffler hit the speed bump but wasn't damaged at all by the impact.