mystery bush

There are two bushes that are on the west side of a gravel driveway in zone 9 where they are exposed to massive amounts of heat and sun. They receive an ample amount of neglect but go like gangbusters every spring and summer. You can see some dead tips of growth from last year, and they are continuing to climb with new green growth in the middle of the third year of California drought. They die back like they look like they're never coming back during the frosts of winter. They have small purple flowers. What are they?

Could be blue potato bush or purple night shade?

I finally found someone who could i.d. this bush and thought I would share the information here. Lycianthes rantonnetti, or blue potato bush, is native to South America. It is a tropical plant, but it is very, very tolerant of drought. It is hardy from zone 8-10, and it dies back in the winter but comes back in the spring. It is poisonous, and my goats won't eat it. It has small purple flowers in the spring. Not sure if bees like them. Basically, it is an ornamental with no other uses than to screen during the summer heat. It is easily propogated with stem cuttings, but there are no seeds. The berries are poisonous. This is great if you want an easy to take care of bush to screen out west sun.