bottom of laptop lose

That could be a swelling battery. If so DO NOT delay having Apple evaluate because swelling increases dailt proiressingely doin more damage until the computer is no repairable.

....but when I touch it sounds like its popping

Don't do that anymore! If the battery is swelling, that could burst the battery core's seal and emit flammable gas.

You appointment at the Genius Bar at an Apple-owned store is free, in warranty or out. But you MUST make an appointment -- they are always very busy.

They will pay attention to you near the appointed hour, but may also be continuing to follow work started with previous users, such as a software re-install.

They will work diligently to diagnose and resolve your issues.

Be sure to be polite and professional throughout the process. If all that is needed is a stray screw or something "fiddled with", there MAY be no charge involved. If PARTS are required, they are subject to standard prices for INSTALLED parts. For example. replacement MacBook Pro "feet" on many models cost about US$10, installed.

If you think there is a physical issue with your MacBook Pro, schedule an appointment at your Apple Store Genius Bar for evaluation and options.