I feel myself a bit spoiled after reading through all the replies in this topic.

The biggest problem in my country is an ageing population and the additional costs this brings for society (because of increasing decline of birth rate).
My country has an excellent social welfare system (incluiding basic state pension for everyone above the age of 67 and unemployment-benefit) and a liberal view of how society should work.
But bringing up all the money that these policies cost to uphold, is one of the (latent) problems in my country for the next 20 or so-ish years.