Should I backup my statements concerning my interest in the field I've chosen with specific examples [in the SOP]?

Some suggest that it is enough to show your interest towards a field of study in the statement of purpose, by writing direct and simple sentences like "This field of study interests me because of X, Y and Z", but I've also heard it from few people that it is very vital to give specific examples of what I have done with my field of study, to backup these statements! What's the best approach? Since SOPs have word limits, it is very a hard task to backup everything with specific examples.

Besides, is it inappropriate to use phrasal verbs in the SOP (but very-very few of them, like one or two of them in the whole text)? (e.g. follow up)