Hometap, a Boston startup that offers homeowners cash in exchange for an equity stake in their house, is gearing up for a major national expansion after raising $100 million from investors hoping to unlock some of the value stored in US residential real estate. The company says it hopes to make its services available to about 75 percent of US homeowners, a signal of the growing ambitions for a novel form of investment that has emerged over the past few years. “It’s a weird new idea. It’s definitely different than your grandfather’s mortgage,” said chief executive Jeffrey Glass, a longtime Boston tech executive and former managing director at Bain Capital Ventures. “But this idea is starting to catch on with people, and people are starting to recognize it as an interesting and credible alternative.” This article originally appeared on The Boston Globe. Read the full article.