Physics for beginners

Soap will make foam.
Foam is light.
Water is comparetively heavy.
If you have foam and water in a semi closed space, and you add water, the foam will go up.
If the opening in question is, say the soap tray of your washing machine, the foam will go through that.

If you walk into the bathroom and everything is incredibly foamy and wet, the first thing that will go through your head is “Did I leave the bath running?” to be quicly followed by “I don’t have a bath” and “I was doing the laundry and accedently put to much soap in the machine, given that I was only washing two pairs of sneakers”. Slowly it dawns upon you. You realize you’re very blond… Beach hair gooood :-)