Talk of bubbles has been coursing through U.S. asset markets lately — from stocks to bonds to real estate to venture capital.

"Everyone, these days, is looking for a bubble here in the U.S.," CNBC commentator Ron Insana writes in a commentary for CNBC. "But it may be more wise to look overseas — to China."

When it comes to Chinese stocks, they're "shooting up like bottle rockets, lifted, in large part, by individual investors," he says. And we're all aware that the excitement of retail investors often signals an overvalued market. "They are often the last ones to arrive at a party, and the first to be carried out the door."

Hong Kong’s Hang Seng China Enterprises stock Index hit a four-year high this week and has soared 19 percent so far this year.

"The speculative excesses on display in China, including a 165-foot tall statue of a bull at the Shenzhen Exchange, is reminiscent of the heady days of individual investors chasing the hot stocks of the 1990s, here at home," Insana writes.

"This all comes as China's exports to the rest of the world dropped 15 percent year-over-year last month. Talk about a bull in a China shop!"

Insana's not the only one concerned about the potential for financial trouble in China. Hank Paulson knows a thing or two about financial crises, having endured a bird's eye view of the 2008 version as Treasury Secretary under President George W. Bush.

And he sees danger in China now.

"It's not a question of if, but when, China's financial system, particularly the trust companies, will face a reckoning and have to contend with a wave of credit losses and debt restructurings," he writes in his new book, "Dealing With China: An Insider Unmasks the New Economic Superpower," USA Today reports.

To be sure, he thinks the Chinese government can manage the economy's problems. "It is important that China stop its over-reliance on municipal debt to finance infrastructure," Paulson tells the paper. "I take comfort in the fact that China's leaders understand this."

And could another financial crisis hit the United States?

"Of course it could," Paulson insists. "But I don't see anything the magnitude we dealt with happening in the U.S. anytime soon. We have already taken some very, very significant steps. Our banks are much better capitalized. They're much better managed. We have better regulation. We have better risk control."

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