Hello Doctors. I'm Asking This Out Of Curiosity: I Had

Hello Doctors. I'm asking this out of curiosity: I had some beer last night and every time I burped I could feel something coming out. When I finally made it to the washroom to "throw up", only white foam came out (I did have some food a few hours prior). I was completely fine after that and this morning. What could possibly have caused the white foam?