Mix of one of the largest flagship universities in the United States, state government of second largest state in the country, a big time music scene, and a lots of tech industries.
Nashville also combines a lot of those things and isn't nearly as liberal as Austin (less Democratic despite also being much less white), so I don't think that fully explains Austin's liberalism (actually, wouldn't the state capital of a conservative state even move it to the right).
Should have noted "public" flagship university, also given current growth and political trends, it wouldn't surprise me if Nashville looks a lot like Austin in 20ish years.
