First, I'm a little confused. What's on your walls BEFORE you apply the KILZ? Wallpaper? A 'first coat' of KILZ? Some other paint (as Pat believes?) Virgin drywall??!
Usually, if you're painting where you get bubbles, it's usually attributed to moisture being on the wall. Then, when the moisture tries to 'get out' from under the paint, it expands and bubbles-up the paint. Now, I'm going to go out on a limb and assume you're painting a bathroom or a house that's very humid inside. If the humidity is high OR the wall are a little wet, it's best to wait until the house (or bathroom or whatever) is DRY, then paint. Give this 'theory' some thought as to where the moisture on the walls is coming from.