Boiler problem

[Belxvs]

I have a condensing boiler in my kitchen and every time I pour waste water down the sink there’s a gurgling noise at the boiler. I do know that the overflow from the boiler runs into my soil pipe and I have checked both waste pipe work and outside soil pipe work at the manhole everything is clear! I would just like to know could this cause problems with my boiler in the future? Any advice appreciate
Many thanks
Anthony