NAR's chief economist Lawrence Yun said the recent rising interest rates may be creating a fence-jumping effect. "Even with limited choices, it appears some of the rise in contract signings could be from buyers wanting to take advantage of current affordability conditions before mortgage interest rates move higher," he said. "This implies a continuation of double-digit price increases from a year earlier, with a strong push from pent-up demand." 

Yun said he expected the national median existing-home price to rise more than 10 percent to nearly $195,000 by year end. This would be the strongest increase since 2005 when the median increased 12.4 percent. 

Existing-home sales are projected to increase 8.5 to 9.0 percent, reaching about 5.07 million in 2013, the highest in seven years; it would be slightly above the 5.03 million total recorded in 2007.