Everyone has experienced the dreaded sink gurgle as the water goes down the drain. This problem is generally caused by a partial block somewhere along the path of the water. There is a blockage either in the trap or else somewhere farther down the line. This problem can be diagnosed and fixed with a little time and the right tools.
Remove the p-trap under the sink using channel lock pliers. The p-trap is directly under the tail pipe coming from the bottom of the sink and is the shape of a half oval.
Examine the p-trap and make sure that there are no clogs in it. Clean it out completely. If it was partially clogged reinstall it after cleaning it out and see if the gurgle is gone.
Remove the p-trap and use a plumbing snake going directly into the straight pipe that goes into the wall. Work the snake out a little at a time and turn it constantly. Extend the snake as far as it will go. Reassemble the p-trap and any other piece of pipe that was removed and test to see if that got rid of the gurgle.
Call a professional if the gurgle persists. The snakes that plumbers have are much better and can cost several thousand dollars which is more than most homeowners would be willing to spend.