When a list of the world's cities most at risk of a housing bubble circulated earlier this fall, the city at the top came as a surprise to many. It wasn't New York, Los Angeles, San Francisco, or San Jose, where less than 40 percent of millennials have been able to apply for mortgages. It wasn't even in the U.S. Instead, it was Vancouver, a city that has experienced a real-estate boom over the last decade as home prices doubled, with the average single-family home now listed at $1.21 million, thanks to an influx of foreign buyers. The impact on Vancouver's housing economy has been so severe that the local government had to impose a 15 percent tax on foreign buyers. Now that the tax has taken effect, though—and subsequent sales from out-of-towners dropped to 0.7 percent in the month following, as CNN points out—a new city has emerged as the next playground for foreign buyers.

Seattle is where international buyers are currently flocking. Home prices have risen 11.2 percent over just the past year, according to S&P CoreLogic Case-Shiller Indices, as foreign buyers have started to account for a whopping 55 percent of all transactions in Washington State, CNN reports.

The shift from Vancouver to Seattle makes sense. Both cities offer the same lush Pacific Northwest landscapes and weather, as Seattle is only 150 miles south of Vancouver. Plus, there's a lot more room for the market to grow in Seattle, where the most expensive home sold this year went for $13.25 million, compared to $31 million in Vancouver.