I store my extra VG nic in the freezer, and it does not freeze solid. It does get extremely thick, though. It needs to warm back up to room temperature to be useful.
From what I have read here, it would appear that it is better to freeze nic for long term storage, rather than refrigerate. Less chance of flavors/odors from the other foods transferring through the storage container that is not as impermeable as it would seem.
It has also been recommended that for long term storage, high strength nicotine should be stored in glass containers. One of the chemistry experts that posts here has stated that high nicotine levels can react with plastic bottles, leaching out some of the plastic components into the liquid. My 100 mg VG in the freezer is in glass, and did not swell or damage the bottle as it would if you were freezing water.