"popping" noise from brakes

[_Leg_]

My MK Indy has started with a light popping noise (it's like air bubbles in water) under heavy braking.

Wondered if anyone had any ideas what it might be please?

The car brakes fine.

[ohtari]

ABS sensor by the sounds of it (assuming you're not hard on the brakes at the time)

Have you checked the pads for wear?

[_Leg_]

Doesn't have ABS I'm afraid.