The gganimate package allows to build animated chart using the ggplot2 syntax directly from R. This post shows how to apply it on a bubble chart, to show an evolution in time.
Before trying to build an animated plot with gganimate, make sure you understood how to build a basic bubble chart with R and ggplot2.
The idea is to add an additional aesthetics called transition_..() that provides a frame variable. For each value of the variable, a step on the chart will be drawn. Here, transition_time() is used since the frame variable is numeric.
Note that the gganimate automatically performs a transition between state. Several options are available, set using the ease_aes() function.

# Get data:
library(gapminder)
 
# Charge libraries:
library(ggplot2)
library(gganimate)
 
# Make a ggplot, but add frame=year: one image per year
ggplot(gapminder, aes(gdpPercap, lifeExp, size = pop, color = continent)) +
  geom_point() +
  scale_x_log10() +
  theme_bw() +
  # gganimate specific bits:
  labs(title = 'Year: {frame_time}', x = 'GDP per capita', y = 'life expectancy') +
  transition_time(year) +
  ease_aes('linear')
# Save at gif:
anim_save("271-ggplot2-animated-gif-chart-with-gganimate1.gif")Since gganimate is a ggplot2 extension, any ggplot2 option can be used to customize the chart. Here, an example using facet_wrap() to use small multiple on the previous chart, spliting the chart window per continent.
Important note: this example comes from the gganimate homepage.

# Get data:
library(gapminder)
 
# Charge libraries:
library(ggplot2)
library(gganimate)
 
# Make a ggplot, but add frame=year: one image per year
ggplot(gapminder, aes(gdpPercap, lifeExp, size = pop, colour = country)) +
  geom_point(alpha = 0.7, show.legend = FALSE) +
  scale_colour_manual(values = country_colors) +
  scale_size(range = c(2, 12)) +
  scale_x_log10() +
  facet_wrap(~continent) +
  # Here comes the gganimate specific bits
  labs(title = 'Year: {frame_time}', x = 'GDP per capita', y = 'life expectancy') +
  transition_time(year) +
  ease_aes('linear')
# Save at gif:
anim_save("271-ggplot2-animated-gif-chart-with-gganimate2.gif")