Housing bubbles can lead to economic disaster. Home prices that rise too rapidly can eventually pop, sending values down and putting home owners at risk.

Certain markets around the world are starting to look “bubbly and some fear they risk putting economies in jeopardy,” Fortune reports. The magazine listed the following five housing markets as ones to watch for possible bubbles: 

• Australia: In Sydney, the country’s most populated city, average home prices surged 13 percent this year to a record $718,122. The rapid rises have even prompted the country's central bank to urge lenders to stop making mortgages so easily available. 
• Brazil: Home prices in Brazil have doubled in five years. In the biggest cities of Sao Paulo and Rio de Janeiro, home prices have increased 188 percent and 230 percent, respectively, since January alone.  
• New Zealand: Prices in Auckland have increased 17 percent. Low borrowing costs have helped fuel the country’s housing market recovery after a near bubble back in the early 2000s, but they're also pushing home prices higher again. 
• China: Prices have jumped by the fastest pace there in nearly three years. In Beijing, prices increased 16 percent and Shenzhen by 20 percent in the past year. But while bubble fears are brewing, residential mortgage debt is relatively low in the country since the Chinese tend to big savers who put their money in real estate, Fortune notes. 
• United States: Some fear that a bubble is brewing again in the U.S. as home prices make a big recovery this year after a 2007 downfall, Fortune reports. Median prices for existing single-family homes have increased 12.5 percent during the third quarter from a year earlier to $207,300. “I’m beginning to see signs not just in my district but across the country that we are entering, once again, a housing bubble,” said Dallas Fed President Richard Fisher last month after a speech in New York. 

Source: Fortune