I think "China Inc" is the biggest bubble going.
I'm old enough to remember the 1980s when all the "experts" were just positive that the world economic superpower of the future was going to be Japan. There was no doubt. Japanese investment in New York and London was met with resentment. Robin Williams joked that Nintendo translated into English meant "We won the war".
You don't hear too much fear of Japan being the future power nowadays.
And the Japanese economy, their political system, their transparent and corruption-free legal system, etc are leaps and bounds ahead of China.
When China's one-child policy yields a nation of 1.4 billion with the average age being over 60, there's going to be some real problems.
When China's policy of raising revenue from the rural peasantry by "selling" them land (confiscated by the communists back in the 1950s) runs out, there'll be fiscal problems.
When Vietnam and the Phillipenes and Burma become cheap labor alternatives to Chinese factories, there'll be problems.
When the people get sick of permanent Communist Party dictatorship (and related obscene levels of government corruption) and political unrest makes China a less attractive investment, there'll be problems.
Not to mention rampant pollution, damaging brain-drain immigration, growing dependence on foreign energy imports, etc.
I predict that 20 years from now people will be shocked that there was once a fear that the Chinese would be the superpower of the future!
Or the European Union.