04 honda civic ex overheating issues?

Ok so I just bought an 04 honda civic ex with 132k. About 2 weeks later started noticing car would goto hot when stopped for about 30 seconds or so but would go normal when moving. Also noticed coolant filling up the overflow and spitting out the top. So replaced the thermostat and it would no longer overheat when stopped fans kicked on correct times etc. Fan also works with a/c on. However after replacing the thermo it still puts coolant into the overflow. And it seems like only when it's middle of the day and hot outside after stopped and idling for more then 3 to 5 min the temp will rise but it won't goto hott it will goto like 3/4 stop and come down. When it's cool outside seems to not do that temp stays under half fans kick on and never rises. Engine oil is clean and not milky car runs great and no loss of power noticed and no smoky exhaust. I also drained and refilled coolant twice after thermo replacement. It's been a few weeks since I replaced the thermo and just added coolant and it took about a water bottle or 2 to top it off again. Don't notice any coolant leaks on the ground or anything. Been reading a lot of post and a lot of people talk about blown head gaskets. Could these issues be a blown head gasket or would I really notice when the head gasket is blown. Also with radiator cap off and car idling coolant will bubble a little bit when reving the car up no bubbles coolant just rises. Is the bubbling normal at idle? Could my radiator may be going bad?

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