As others have mentioned, it sounds like delamination. In most cases, this is a sign of water damage. not only do you need to address the damage, but need to know what caused it and repair that.
If you're able to repair this type of damage, you can get some sweet deals. if not stay well clear.
Below is a link to damage repair where the entire wall was literally rotted away. major work to rebuild the interior and exterior walls and structure.
Repairing Delamination and water damage | 2001 Coachmen Mirada 300QB
This link is to repair of minor damage, but looked absolutely horrible.
Repair interior wall de-lamination damage | 2001 Coachmen Mirada 300QB
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