My dad did similar to an early 2000's builder grade GE Potscrubber. It was an awful excuse of a machine anyway, but he decided that adding a few drops of liquid detergent took the grease off better.. That worked fine for a few washes until it didn't anymore, and we walked into the kitchen to see a cascade of foam coming out at the bottom of the door with each revolution of the spray arm. We had owned a dishwasher for several years by then, so he should have known better LOL. My mom and I never did let him forget about that one!
Also had an incident where one of the kids I worked with at a summer camp (16-17 at the time) had changed the detergent bottle on the commercial dishwasher (automatic dispenser system) and used "pots and pans" detergent rather than the dishwasher detergent.. That was a foamy mess for sure! Each time the wash cycle started, suds would shoot out around the doors. I was laughing too hard to be mad, but I made sure to explain the difference before it could happen again. In their defense they did come in very similar bottles by the same brand. Cleaned the dishes decently until we figured out what had happened though!