Hi, the sink in our master bathroom is 'burping' about 2-3 seconds after we turn off the water IF we are draining anything other than water(like toothpaste, hand soap, etc). If it is just water it does not do it. I have so far tried the bleach/hot water suggetion on this site and that did not work. I then tried drano twice and it still did not work. Finally, I removed the stopper & managed to pull out a huge clump of hair and to my amazement the sink is still burping! The funny thing is the sink drains fine, but this noise it makes is driving me crazy. Is there any other DIY stuff I dare try or is it time to call in a plumber? Thanks!