Take stocks or real estate. The price goes up. People see the price going up. They buy, because they want to buy something where the price is going up so that they will make money. That buying increases demand without increasing supply, so the price goes up some more. That's a bubble - where the price goes up because people are buying because the price is going up (and so they think it's going to keep going up). It's a positive feedback loop.
But bonds... nobody's buying bonds because they think the price is going to go up. They're buying bonds because they think bonds are safe. But, in fact, bonds aren't very safe. The next direction interest rates will move is up; when they do, bond prices will fall. The longer term the bonds, the more the price will fall.
Note well: I am not an economist. I am not an investment advisor. This is my understanding of how things work, but it is not financial advice.
Long, markets-wide, diversified positions tend to work out best for retail investors. Switching from heavy positions in one asset class to heavy positions in another tends to benefit investment firms, without reliably lowering investor risk. It's hard to guess where the market is going, and the transaction costs of frequent position changes, even at institutional investor rates, can quickly outstrip gains of a correct guess.
You know better than anyone about your own goals and progress, so you can make reliable decisions based on that information.
No one knows what the market is going to do next, and even if we assume a range of predictive accuracy, you're probably low in that range unless you spend a tremendous amount of time getting and analyzing economic data. So, you can't make reliable decisions based on that information.
the winning game: 1) invest in broad-based, low-fee indices as regularly as you can. 2) try to forget about them.
Be cautious investing in bonds, and if you do, you might consider holding them to maturity if interest rates go up and prices/value goes down (and hope they don't get called).
I personally think it's a scary time - interest rates going up will have an effect on prices of bonds, stocks, and more. So while you earn more interest if you own fixed income assets, the value of those assets decreases and you can get stuck.
That said... IMHO, the raising of interest rates... I think really needs to start happening before the artificially low rates creates a different kind of animal altogether.