Yesterday, while playing Civilization V: Brave New World game, I suddenly researched Refrigeration Technology, even though I was researching Atomic Theory (had 5 turns left on it).
How could this have happened?
I'm sure it wasn't from esponiage as I do not have any spies trying to steal technology from other civilizations.
Come to think of it, can City-States gift free technologies?
(I have all the policies in the Patreonage tree)