Yes I have done that, went to Cambodia spent 15 months in a self funded volunteer capacity in my field of diagnostic medicine assisting and teaching their people. It was the most challenging and rewarding experience in my life but the personal financial cost of loss of income for that period was significant but in my mind still worth it.
I wanted to do this when I was younger, was planning on heading to England but it would have been to hard on my parents so just went for holiday instead