Whoa! What just happened?

This is my sister's China Glaze Crackle Glaze that was purchased last year and what has become of it now.

So has this ever happened to you? Or I mean your nail polish? It's completely dried out (and kind of scary looking).

The funny part is, it only happened to hers. The ones I have are still fine (for now?). Anyone know why this happened? I'd love to hear your thoughts! I'm thinking it wasn't closed tightly enough. 

Thanks for reading!