toliet is bubbling

When I use my shower, my toliet bubbles likes it’s going to erupt. I have had the plumber out twice and he has snaked it each time. Once part way and once all the way to the street. I noticed we had this same problem last year when we had a lot of rain but my husband thinks there is no connection. I already called the city and they said there is no connection. Help, it is still bubbling. I’m getting afraid to shower.