tmpfs'es get accidentally unmounted

I use tmpfs for a fast dependency cache: for example, for Golang (~/.cache/go-build), or for Node.JS (node_modules in project folders). Though accidentally they disappear. Sometimes all, sometimes a part of them.

AFAIR, it happens even when nothing touches these folders.

Can the kernel do it automatically to free the memory? I see no any entries in dmesg when this happens. Or do I have to hunt the cause in the user space?