Anti lock system maybe If this is a front wheel drive vehicle you may have a cracked axle,,,,,causing the popping noise when turned and under hard braking.
No it is not normal. I am not a mechanic but whenever my brakes make a clicking sound or poping sound, I think there might be something loose or stuck in the brakes. The first thing I would do is elimante other noise sources such as ball joints, etc. Then I would have someone walk beside the vehicle while I reversed to pinpoint if the noise is from the rear or front. Chances are it is the rear brakes if they are drum brakes. Sometimes, it is also a sticking brake shoe that is okay when the wheel goes forward but gets caught for a second when the wheel goes in reverse. My advice is that if you have not worked on brakes before, see a mechanic. An adjustment might be all you need.
my guess would be to have your brakes checked... or maybe you are dragging something...
I would advise bringing your car to a mechanic as quickly as possible. Your brakes could fail. This puts you at a high risk for injury or even death.
Could be the brakes are metal to metal.
vacuum leak
Yes.
you would still hear the sound because of the sound's echo
sound like you have "grabbing" brakes to me. i would check them for contamination and if they are then you will need new brakes and to replace all rubber components, and if your brakes are not contaminted i would start checking wheel bearings, warped rotor or drum, and the balance of your tires. i would check your rotor or drum first, that is most likely the cause
Most common cause would be a loose brake caliper mounting bolts.
It's probably a loose suspension or brake component and the axle assembly is shifting slightly when you hit the brakes. I'd have to hear it to be sure.
The most likely source of a crunching sound in your basement ceiling would be mice.
Sounds like a torn/ loose/ holed vacuum line.