It can be alarming if your chest pops when stretching your rib cage. However, this is not usually painful and can occur when gas is released from your joints.
When chest pain is “just” costochondritis
Why is my chest popping every few minutes? I notice this when I purposely stretch every few minutes because it really bothers me. Before I pop my chest by stretching, I get
Uneven rib cage: Causes, treatment, and when to seek help
How to Fix Snapping Scapula Syndrome - Posture Direct
Why Does My Rib Cage Pop When Stretching?
Slipping Rib Syndrome: A Case Report
Is it normal if the bottom part of my ribcage can pop out? - Quora
Should You Pop Your STERNUM? (For Costochondritis)
Slipping Rib Syndrome - Physiopedia
Pregnancy Rib Pain - Maternal Massage
Rib Flare: Why it Sucks and Why You Should Care