Who hasn't found that one of their favourite nail polishes has gone gluggy when they went to use it?

Apart from buying nail polish thinner, what can you do? Well prevention is always better than finding a cure, so it is pretty simple. 

Always store your polishes UPRIGHT!!!! That is ALL you need to do.  Don't put them on their sides in a basket, just store them upright like little soldiers in or on a cabinet table top type surface.

You will never find a polish that has defected to the gluggy side!