My wife mentioned she hear's liquid running the dashboad? I told her she was crazy until I heard it!

When the brakes are gently applied it sounds like water/liquid running from the back of the car to the front of the car, I have no idea what this is.

I've only owned toyotas and this is my first camry, is what I'm hearing normal, what is it?

Thanks in advance for your reply.
-trev