Major review for the second time I submitted a research paper to a journal in March 2015. One a half month later I got back a major review from one reviewer and a minor from the other. Overall, it was classified as major revision.

It took me two months to inculcate all the suggested points and I re-submitted the improved version on the 3rd of July. The status immediately changed to under review. Since the original reviewer who suggested major revision could not review it this time, the services of a third reviewer were acquired. After four and half months (on 13th of November), I got back yet another major revision.

Is it normal to have a paper reviewed by another reviewer? And what can be the probable outcome? My colleagues were telling me that major review for the second time is very concerning.
It is difficult to see what other alternative the editor has; given that problems were identified in the paper by the original reviewer, the editor need to be confident that these have been adequately addressed, and a good journal should not base their decisions on the view of a single reviewer.  I'd say it is perfectly normal, and beneficial.

If the second reviewer has identified further shortcomings in your work, while that it perhaps not what you were hoping for, but in the long run I suspect they have done you a favour as it will strengthen the paper that is finally published.  I wouldn't be too concerned by this, just address the new set of criticisms as well as you can and resubmit.

What is not really acceptable is for a reviewer to give one set of comments, which you then address, and then for the same reviewer to give another set of criticisms about the revised version that they could have made in their original review.  However as this is a new reviewer, I don't think there is a real problem.