In my half bath, when I drain the sink, the toilet bubbles. I have a snake but sure would appreciate some expert advice of what I should do to fix this.
Thanks!

The bubbles is your clogged vent stack trying to vent through the toilet. Rod the stack from the roof with enough rod to reach roof top to basement plus 20'

It's seldom I disagree with Bob but
Bubbles indicate a blockage in the drain line.
Gurgles indicate a blocked vent that's attempting to vent through a trap.
The solution would be to snake from the lavatory roof vent or pull the toilet and snake from there.
Good luck, Tom

So - snaking the sink won't help? I am not sure how to snake the lavatory roof vent - but I can pull the toilet and snake it from there. I was hoping snaking the sink would work because that's easier than pulling the toilet. If this doesn't work, I will have to call a plumber because I don't want to go on the roof.
Thank you! :-)

Snaking the lavatory would stop you at the tee UNLESS you removed the "J" bend from the trap and went in the wall with a swivel head auger,m (see image)
That way the snake would be directed down from the tee into the drain, (6the same as if you went down the roof vent.)
The only other way would be to pull the toilet and snake from there. Good luck, Tom

Do you have cleanouts for the sewerline outside the house? If so check them and see if there is water holding in the line, it may be plugged down stream of the cleanout. Goodluck