Just had a surprise. I have a section in an article followed by a figure. The text flows over a page and ... one more word on the next page (which also includes the figure).
Yes, I added a ~ before that word to make it fit on the first page but I thought LaTeX wouldn't do this (leave widow words, not even sentences)!
Is there anything in particular that needs to be enabled to avoid this? I used MikTeX 2.8 with output to PDF (both pdftex and pdflatex produced the same problem).