I went through this with my DS at this age. He was so danged snarky I was tempted to just walk away. The advice I got here then was really great.
It has to do with a hormone surge that is very similar, some say worse, than the teenage years. They are becoming big kids, and like teenager, this is both exhillerating, and terrifying at the same time. They are more capable than they have ever been and yet they need you more than ever. Part of it is testing boundaries, part of it is just a lack of impulse control, mood swings, and general lack of communicative skills. It's NOT personal, and I don't think there is much you can do to avoid it...some people might get lucky, but it's just luck.
One thing I did with my DS when he would say "ugh, just leave me alone, MOMMY!" was say "It sounds like you want some time alone. Try 'Mommy, I'd like some quiet time to myself please.'" and then wait until he repeated it. Then I'd say "no, problem pal. We all need that. I'll be here when you're ready."
Generally speaking people are aggressive because their needs are not being met. Helping them get to the root of their attitude gives them the skill to ask for a need to be met. I also found that increasing the protein intake at breakfast and steering clear of things with food coloring and corn syrup helped a lot in keeping DS more calm and capable of remembering his polite words.
I also used to say to the Nevers " Never, ever? Like forever? Wow...that's a long time. How about we just take a break and if you feel like changing your mind, I'll be here for you."
Then when things have calmed down have a talk about words and hurt feelings. It does pass! But then it might come back again later.
Other things that helped during this phase was to re-evaluate our house rules, for example we gave DS a small allowance in exchange for some chores which made him feel very grown up to be allowed to decide what to do with his money, and to contribute to the household in real ways.