car dropping temp randomly

went for a run up palomar mountain today. car ran fine all the way up and at normal temp and i was running at high rpms the whole time. we stopped at the top and let are cars chill for a little while then headed back down. i cruised the whole way down and the temp was still running at about 210. but once i got to the bottom its just dropped to were the gauge was reading zero. i pulled over to check it out and there was a little smoke and it smelt weird too. i let my car sit for about ten minutes and the temp started to climb again so i decided to head home and it just chilled around 210 again and the smell went away. im drawing blanks on this and so are my friends are too, can anyone help me out with this?

VigLink badge