This is believed to be due to air being pushed out of the gap between the lid and the toilet bowl by the water flow. When the toilet is flushed with the lid closed, the aerosol effect may be ...

If there's a problem with one of these parts, the flow of water into the toilet bowl will be restricted ... smells ...

You should also check that the water flow is turned off ... from the sink if needed – this prevents air pockets. Lower the plunger into the toilet bowl at a slight angle to avoid introducing ...

If you have a bellows-style plunger, fill it with water before you put it in the bowl. The reason for this is simple. Air is compressible, and some will inevitably get in the toilet trap.