Nope. Your boss, via the IT department, could pull up the access records for every single site you visit based off the MAC address of your NIC. If you went to a proxy page, they would then only be able to tell you went to a proxy site, but that too would possibly arouse suspicion. Basically, if you think about it, if you go to some website, that website's server has to know how to get the data to you. So what you want is sort of like sending a letter to Steve in New York City. No last name, no address, just "Steve". There's probably hundreds of Steve's in NYC, so the odds of the letter getting to the Steve you intended it for is unlikely.
My advice would be first to look at any employee handbook you may have, make sure to read the policies on personal web browsing. Some companies aren't going to worry about it so long as you aren't doing anything illegal or streaming 1080p movies from your Netflix account and soaking up all the bandwidth for everyone else and you're getting your work done that they pay you for. Other companies are extremely up tight about this sort of thing, and are always on the lookout for people using the Internet for non-work things. If you have any doubts about which your company is after reading the handbook, talk to your boss and/or someone in HR about it. Finally, if you have any doubts even after that, the safest option would probably be to just wait until your lunch break or you're off work when you can go to a nearby Starbucks or use your personal Internet connection at home.