Demand is way up and inventory is way down. That means buyers are all chomping at the bit to bid on the few houses that are on the market. "I’ve had clients this spring who have offered on properties without even seeing them," explained realtor Kerrianne Ciccone.

In the most popular neighborhoods, sellers are routinely getting multiple offers above the asking price. While that may sound like great news for Ciccone’s clients, it can create some problems. "You never quite know what you are going to get into when you sell your house," Maniar said.

One of the biggest unknowns in the current market is the appraisal, writes CBS Boston. If a bidding war pushes the price above asking, the appraisal may come in too low.