I get this weird bubbling noise when breaking coming from the passenger side of the dashboard. It doesn't happen all the time but quite often. Seems to be happening more when driving short distances. Any ideas?

Do you have cross drilled rotors? Are the windows down when you hear this?

I have stock rotors and windows were closed. Breaks have been flushed a month ago.

Could it be from the A/C?

Coolant moving around in the heater core, or water buildup (plugged drain) in the A/C evaporator casing?

Any idea how can I determine if any of these two are causing the bubbling noise?

Run the A/C a while, long enough to generate condensate, & verify that it drains out onto the ground.