What does the phrase "in fits and spurts" mean?
I met this expression in some articles, but I don't quite understand what exactly it means. Could you help me with some explanations? Thanks.
Some example sentences are as follows.

Inspiration comes in fits and spurts, laced with time, warmed with the heart.
In fits and spurts, The Iron Lady does convey the hardships and price of power, particularly given Thatcher’s gender.
Muller said global warming continues but in many fits and spurts.
Like many human relationships, the end comes in tiny fits and spurts, ultimately leading to a full break up.

Question

What does the phrase  "in fits and spurts" mean?
I met this expression in some articles, but I don't quite understand what exactly it means. Could you help me with some explanations? Thanks. 
Some example sentences are as follows.

Inspiration comes in fits and spurts, laced with time, warmed with the heart.
In fits and spurts, The Iron Lady does convey the hardships and price of power, particularly given Thatcher’s gender. 
Muller said global warming continues but in many fits and spurts.
Like many human relationships, the end comes in tiny fits and spurts, ultimately leading to a full break up.

Answer

I just wanted to add to what Mr. A already wrote that I think of “in fits and spurts” as a (less common) variant of “in (or by) fits and starts” which means “with irregular bursts of activity”: “the economy was recovering in fits and starts”  
(http://www.oxforddictionaries.com/definition/english/in-or-by-fits-and-starts?q=fits+and+starts)

Answer

"in fits and spurts" means something like "unpredictably, and suddenly"