My toilet, a Dometic 320, has suddenly started acting like there's a vapor lock when I flush it. I step on the pedal and it burps and sometimes even burps so bad it splashes some on the floor. What is...
As Rhagfo suggests, you have developed a pile of poo and tp at the bottom of the pipe. This normally happens because folks flush the toilet without using enough water. You'll need to physically bust up the pyramid. One way to do that is to stick a water hose down the open toilet and flush away the pile. Once clear, make sure you use enough water whenever there are any solids being flushed.