I hear bubbling when I do a boost leak Test??

[TooFastTooG]

Ok so when I do a boost leak test, I hear a sound as if bubbles are escaping into some type of liquid sourse, it sounds like its coming from the lower part of the engine. Its not a hissing like a normal boost leak, but like as if you were blowing bubbles when you are swimming. I find this very odd because is there any sort of liquid that comes in contact with all my vacuum lines? Please help WTF

 

[xveganxcowboyx]

Take off your oil cap and listen. See if the noise is coming from there.