It's not just in China either. major cities in the US and Europe are seeing huge amounts of property being purchased by Chinese nationals, and then not used, or being rented out at a break even. The thing is, Chinese have nowhere to put their money - bank accounts pay nothing and anyway aren't safe from the government. Stocks don't really exist as an option, and so the Chinese put any saved money into apartments, and because Chinese perceive 'used' apartments as being worth less, those apartments stay unused, not even being rented out. It's going to end in some serious tears sooner or later.
It's possible that China is facing another crash because of the real estate market. Mr. Wang notes that its economy is slowing, but debt levels are still climbing. Also real estate prices are rising, but lots of sites are empty, so it's possible that this will create a climate for a huge crisis. Not sure about biggest in history simply because there's plenty of history to be made.
We all remember 2008, the infamous year when the housing market in the United States came crashing down. People may advertise real estate as an amazing investment. However, we would all be wise to remember that every investment comes with a hefty price if it doesn't work out. And real estate seems particularly poised to make that fall.
Real estate was not the biggest bubble in history. Student loan debt is a larger bubble than the housing crisis was. Millions of households are burdened with high student loan debt - student loan debt which is keeping people from buying homes and starting families. This has impacted our economy's growth. When the bubble burst, it will have devastating economic impacts.