Generally it doesn’t, but if you have the OPV pressure set low, you can find the machine occasionally ‘burps’ the excess steam pressure into the water tank.
Ah - the OPV was set really low (2.5 bar) when I initially tested it, and I’d been having trouble with steam beforehand - noticed it was doing exactly as you described, burping into the tank and generally steaming badly. Hopefully it’ll be working a bit better now.
Also, how will the OPV setting affect steam?