Sounds like he may be trying to shed? What's his humidity like? Being too dry might cause the popping sounds you heard & also yawning, to loosen the
skin around his face in order to shed. Try spraying him with water. The fact that his cage was too warm may have dried out his skin, making it harder to shed.
(-do you know when he shed last?)

As far as the pics above where he's stretching upwards...what's overhead? A screen top? If so, he might be wanting out, or the cooler air outside his cage
that was overly warm (earlier).