There is the most awful crimes being committed to thousands of innocent bottles of nail polish all over the world. This crime??......... polish remover being used to thin down gloopy nail polish. But there is nothing wrong with that or is there?????
The short and simply answer is YES!!!!!!! Polish remover is made of acetone and this is designed to dissolve the chemicals in the polish and remove it from your nail. What has happened to your polish is that some of the chemicals that evaporate in order for it to dry has escaped from the bottle and need replacing and thankfully such a product exists.
Nail polish thinner or restorer is now very widely available and contains the chemicals that you need to restore your favourite polish. There are many out there depending on your price point at the top of the scape you have Seche Retore, this comes from the same people that make the amazing Seche Vite Top Coat. The one that I have at the moment is from Pretty. I got this from eBay and I have used it a few times and so far it has been amazing. The key to this is to add a little at a time to gradually thin down the consistency. Add a few drops then roll the bottle (never shake that caused bubbles) between your hands and test the polish on a nail wheel or nail tip.
Simple maintenance of your polish bottles can reduce the amount of evaporation like ensuring that the lids are on tight enough. If you spot that there is a build up of polish around the rim then this can allow air into the bottle so every now and then give them a wipe round with some cotton lightly soaked in remover and wipe around the top.
So if you are ever tempted to just pop a bit of remover into a gloppy polish STOP!! It will render it unusable for the future!