Singapore is an expensive country to live in. However, Singapore has been blessed with an ideal location, good governance as well as a stable economical, political, social and technological environment.
On the other hand, Singapore lacks space, ie, land. Land is scarce on that island and this in turn drives property prices up as there is a continuos demand for land but the supply of land is limited. This makes rental there expensive. Majority of its citizens live in high rise condominiums and is only the elite few who have landed property.
I don't think Singapore's bubble is going to burst anytime soon as where land & rental is concerned, Singapore is working on the problem by reclaiming land from the sea and this reclaimation works has been going on in various parts of the island for a very long time already.