Generously grease a 10-inch Bundt pan with butter and dust with flour.
In a medium bowl, whisk together the 2 1/4 cups flour, baking powder, baking soda and salt. Set aside.
In a stand mixer fitted with the paddle attachment, cream the 4 tablespoons butter and the sugar on medium speed until light and fluffy, 3 to 4 minutes. Scrape down the sides of the bowl and then beat in the eggs, one at a time, beating well after each addition. Scrape the bowl again, then add the vanilla, lemon zest and lemon juice. Beat until combined. On low speed, add the flour mixture in three parts, alternating with the yogurt; mix until fully combined. Fold in the blueberries by hand.
Spoon the batter into the prepared Bundt pan and smooth the top with a rubber spatula. Bake until an inserted toothpick comes out clean, 30 to 40 minutes. Cool the cake in the pan on a rack for 10 minutes. Place a plate over the pan and invert the cake onto the plate.
For the glaze: Combine the water and sugar in a saucepan over medium heat. Bring to a boil, stirring to dissolve the sugar. Remove from the heat and stir in the lemon juice.
Transfer the cake to a platter and brush the glaze over the cake, letting it soak in. Let cool.
For the candied lemons: Combine the 1 cup sugar and the water in a medium skillet. Simmer over medium heat until the sugar has dissolved. Add the lemon slices and continue simmering until the rinds are soft, 15 minutes. Sprinkle 2 tablespoons sugar on a baking sheet lined with parchment. Place the cooked lemons on the sugar; then sprinkle with another 2 tablespoons sugar. Let dry at room temperature until tacky, about 1 hour.
Decorate the cake with candied lemon slices.
The candied lemons can be made a day ahead and refrigerated.