Is there a way to tell your boss you want to leave...nicely, without giving your 2 weeks?

I'm very frustrated with my job and I want to look for other employment. I want to give my 2 weeks but I don't want to leave this job until I have another one. That itself will be tough enough! Could/Should I tell my boss that I'm teetering towards the door, or should I sneak around and not say anything? It is going to be hard to find time for interviews while working, but I worry that's the only way! What do you think? Esp. if they ask me why I need to take so-and-so day off!